Duplicating masters by the manifold process

ABSTRACT

AN IMAGING MEMBER CAPABLE OF PRODUCING A DUPLICATING MASTER AND METHOD OF IMAGING WHEREIN AN IMAGING MEMBER COMPRISING A DONOR SUBSTRATE, A PHOTORESPONSIVE IMAGING LAYER OVERLYING SAID DONOR SUBSTRATE, A DUPLICATING LAYER CONTIGUOUS WITH SAID PHOTORESPONSIVE LAYER AND A RECEIVER SHEET OVERLYING SAID DUPLICATING LAYER IS EXPOSED TO AN IMAGEWISE PATTERN OF ELECTROMAGNETIC RADIATION WHICH IS ACTINIC TO SAID IMAGING LAYER WHILE THE IMAGING LAYER IS SUBJECTED TO AN ELECTRIC FIELD. WHILE UNDER THE ELECTRIC FIELD, THE DONOR SUBSTRATE AND RECEIVING SHEET ARE SEPARATED WHEREBY THE IMAGING LAYER AND DUPLICATING LAYER CONTIGUOUS THERETO IS FRACTURED IN IMAGEWISE CONFIGURATION PROVIDING A DUPLICATING MASTER WHICH WHEN CONTACTED WITH A COPY SHEET REPRODUCES THE IMAGE ON THE COPY SHEET.

Feb. 23, 1971 CLARK 3,565,612

DUPLICATING MASTERS BY THE MANIFOLD ROCESS Filed Jan. 9, 1967 ACTIVATE I I 000 @2 0 I; a tub s; 0: s n;- 9 0 0; 2 1- V//////////////////// I ,8 SANDWICH APPLY FIELD AND EXPOSE I SEPARATE F/G. 3b

INVENTOR. HAROLD E. CLARK ATTORNEYS United States Patent M 3,565,612 DUPLICATING MASTERS BY THE MANIFOLD PROCESS Harold Ernst Clark, Penfield, N.Y., assignor to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed Jan. 9, 1967, Ser. No. 608,155 Int. Cl. G03g 13/22 U.S. Cl. 96-1 Claims ABSTRACT OF THE DISCLOSURE An imaging member capable of producing a duplicating master and a method of imaging wherein an imaging member comprising a donor substrate, a photoresponsive imaging layer overlying said donor substrate, a duplicating layer contiguous with said photoresponsive layer and a receiver sheet overlying said duplicating layer is exposed to an imagewise pattern of electromagnetic radiation which is actinic to said imaging layer While the imaging layer is subjected to an electric field. While under the electric field, the donor substrate and receiving sheet are separated whereby the imaging layer and duplicating layer contiguous thereto is fractured in imagewise configuration providing a duplicating master which when contacted with a copy sheet reproduces the image on the copy sheet.

The present invention relates in general to imaging and, more specifically, to a novel method for the formation of duplicating masters. Further, the present invention relates to a modified form of manifold imaging wherein the receiver sheet is coated with a layer of soluble copy-producing material dispersed throughout a suitable binder material.

Although imaging techniques based on layer transfer of a colored material have been known in the past, these techniques have always been clumsy and difi'icult to operate because they depend upon photochemical reactions and generally involve the use of distinct layer materials for the two functions of imagewise transfer and image coloration. A typical example of the complex structures and sensitive materials employed in prior art techniques is described in US. Pat. 3,091,529 to Buskes. Not only does this type of prior art imaging system tend toward complexity in structure in that it employs separate materials for final image coloration and image-wise transfer, but, in addition, image-wise transfer generally depends upon a photo-induced chemical reaction which changes the adherence of the layer so exposed. The effectiveness of this type of photochemical reaction depends, in turn, upon the vagaries of catalysts used in this system, temperature, pH and many other factors which influence the speed and effectiveness of chemical reactions in general. Many of the prior art systems employ light-sensitive diazo compounds which are, of course, notoriously slow in their response to light. In addition, because of the complexities and critical nature of prior art systems they are, for the most part, difficult and expensive to prepare in the first instance and then can only be used by trained operators.

In co-pending application Ser. No. 452,641 filed May 3, 1965 now abandoned, there is disclosed a new and improved manifold imaging method wherein a layer of a cohesively weak photoresponsive imaging material is deposited upon a suitable substrate. The imaging material is activated by treating it with a swelling agent or partial solvent which serves the dual function of making the top surface of the imaging layer slightly tacky and, simultaneously, weakening it structurally so that it can be fractured more easily along a sharp line which defines the 3,565,612 Patented Feb. 23, 1971 image to be reproduced. The activation step, however, can be eliminated if (1) the layer retains sufficient residual solvent from the coating operation; (2) the imaging layer is sufiiciently inherently weak so that it will fracture as desired; or (3) the receiver sheet is coated with a material which, when heated, will fiow into the imaging layer and weaken it so that it will fracture in image-wise configuration. Once the imaging layer is activated, a receiver sheet is laid down upon its surface. An electrical field is applied across the manifold set while it is exposed to a pattern of light and shadow representative of the image to be reproduced. Upon separation of the donor substrate from the receiver sheet, the imaging layer fractures along the lines defined by the pattern of light and shadow to which it has been exposed. A portion of the imaging layer is transferred to the receiver sheet while the remainder continues to be adhered to the donor substrate so that a positive image is produced on one support member while a negative is produced on the other.

It is an object of the present invention to provide an imaging process for producing a duplicating master.

It is an object of the present invention to provide an imaging process for producing a spirit duplicating master which, after the spirit duplicating copies have been run therefrom, is still opaque in image areas and can be used as a projection transparency.

A still further object of the present invention is to provide an imaging process for simultaneously forming a positive or negative spirit duplicating master and a corresponding negative or positive projection transparency.

A still further object of the present invention is to provide an imaging process for simultaneously producing a projection transparency and a duplicating master having a transferable material of latent color potential which, when reacted with a reaction partner, will produce an intensely colored substance.

A still further object of this invention is to provide a novel imaging member in the form of a manifold set.

The above and still further objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed disclosure of specific exemplary embodiments of the invention.

The above and still further objects may be accomplished in accordance With the present invention by providing a donor substrate having a cohesively weak photoresponsive imaging material thereon and a receiver sheet having coated on one surface thereof a uniform layer of a soluble copy-producing material dispersed in a wax or resin binder. For brevity, the coating on the receiver sheet will be called the duplicating layer. After activation of at least one of the imaging material or the duplicating layer with an appropriate swelling agent or partial solvent, the coated surfaces of each supporting member are placed in contact with each other whereby a bond is formed between the coated materials. An electrical field is then applied across the manifold set While it is exposed to a pattern of light and shadow representative of the image to be reproduced. Upon separation of the donor substrate and the duplicating layer-coated receiver sheet, the weakly photoresponsive imaging material fractures along the lines defined by the pattern of light and shadow to which it has been exposed. Because of the cohesive bond formed at the interface between the imaging material and the duplicating layer, these latter materials will be transferred as a single unit. Thus, certain portions of the imaging material will be transferred to the receiver sheet and will completely cover the underlying duplicating layer. In the remaining areas, the imaging material will remain adhered to the underlying donor substrate but will be overcoated with the duplicating layer which is stripped away from the receiver sheet. In this manner and 3 depending upon the exposure, a positive or negative spirit duplicating master will be produced on the donor substrate and a corresponding negative or positive will 'be produced upon the receiver sheet. If the receiver sheet is transparent or uniformly translucent it can be used as a projection transparency.

The nature of the invention will be more easily understood when it is considered in conjunction With the ac- 'companying drawings of exemplary preferred embodiments of the invention wherein:

FIG. 1 is a side sectional view of a photosensitive imaging member for use in the invention;

FIG. 2 is a side sectional view of an alternate embodiment of the imaging member;

FIG. 3 is a process flow diagram of the method steps of the present invention; and

FIGS. 3a and 3b are side sectional views diagrammatically illustrating the process steps of FIG. 3.

Referring now to FIG. 1 of the drawings, there is seen a supporting donor substrate 11 and an imaging layer generally designated 12. In the manufacture of the imaging member, herein referred to as the manifold set, layer 12 is coated on substrate 11 so that it adheres thereto. In this particular illustrative example, layer 12 consists of photoconductive pigment 13 dispersed in a binder 14. This two-phase system has so far been found to constitute a preferred form for imaging layer 12; however, homogeneous layers made up, for example, of a single component or a solid solution of two or more components are employed where these layers exhibit the desired photoresponse and have the desired physical properties. The basic physical property desired in layer 12 is that it be frangible, having 'a relatively low level of cohesive strength either in the as-coated condition or after it has been suitably activated as described more fully hereinafter. Since layer 12 serves as the photoresponsive element of the system as well as the colorant in at least one of the states in which the separated masters will exist, the components of this layer are, in most cases, preferably selected so as to have a high level of photoresponse while, at the same time, being intensely colored so that a high contrast image can be formed by this high gamma system. Thus, for example, in the two-phase system, intensely colored photoresponsive pigments such as phthalocyanine blues, quinacridone reds and the like are preferred. The crystalline forms of metal-free phthalocyanine, for example the alpha form, are especially preferred pigments for use in the invention because of their very high sensitivity. It is to be understood, however, that since the binder itself may be dyed or pigmented with additional colorant in either the single-phase or two-phase system, intense coloration of the photoresponsive material itself, while being preferred, is not critical in any sense even for high contrast imaging. Accordingly, even transparent materials may be used.

Any suitable photoresponsive material may be employed in this system with the choice depending largely upon the photosensitivity required, the spectral sensitivity, the degree of contrast desired in the final image, Whether a heterogeneous or a homogeneous system is desired and similar considerations. Typical photoconductors include substituted and unsubstituted phthalocyanine, quinacridones, zinc oxide, mercuric sulfide, Algol yellow (Cl. No. 67,300), cadmium sulfide, cadmium selenide, Indofast brilliant scarlet toner (C.I. No. 71,140), zinc sulfide, selenium, antimony sulfide, mercuric oxide, indium trisulfide, titanium dioxide, arsenic sulfide, Pb O gallium triselenide, zinc cadmium sulfide, lead iodide, lead selenide, lead sulfide, lead telluride, lead chromate, gallium telluride, mercuric selenide, and the iodides, sulfides, selenides and tellurides of bismuth aluminium and molybdenum. Others include the more soluble organic photoconductors (which facili tate the fabrication of homogeneous systems) especially when these are complexed with small amounts (up to about 5%) of suitable Lewis acids. Typical of these organic photoconductors are:

4,5 -diphenylimidazolidinone;

4,5 -diphenylimidazolidinethione;

4,5 -bis- 4-amino-phenyl -imidazolidinone;

1,5 -di-cyanonaphthalene;

1,4-dicyanonaphtlralene;

aminophthalodinitrile;

nitrophthalidinitrile;

1,2,5 ,6-tetraazacyclooctatetraene- 2,4,6,8);

3 ,4-di (4-meth0xy-phenyl -7,8-diphenyl- 1 ,2,5,6-

'tetraazacyclooctatetraene- 2,4,6,8)

3 ,4-di (4-phenoxy-phenyl) -7,8-diphenyll ,2,5,6-tetraazacyclooctatetraene- 2,4,6,8

3 ,4,7,8-tetramethoxy-1,2,5,6-tetraaza-cyclooctatetraene- Z-mercapto-benzthiazole;

2-phenyl-4-diphenylidene-oxazolone;

2-phenyl-4-p-methoxy-benzylidene-oxazolone;

6-hydroxy-2-phenyl-3 (p-dimethylamino phenyl) -benzofurane;

6-hydroxy-2,3 -di-(p-methoxyphenyl) benzofurane;

2,3,5 ,6-tetrap-methoxyphenyl) -furo- 3,2-f benzofurane;

4-dimethylamino-benzylidene-benzhydrazide;

4-dimethylaminobenzylideneisonicotinic acid hydrazide;

furfurylidene- (2 -4-dimethylamino-benzhydrazide;

5 -benzilidene-amino-acenaphthene 3 -benzylidene-amino-carbazole;

(4-N,N-dimethylamino-benzylidene -p-N,N-dimethy1- aminoaniline;

( Z-nitro-benzylidene -p-bromo-aniline;

N,N-dimethyl-N'- 2-nitro-4-cyano-benzylidene) -pphenylene-diamine;

2,4-diphenyl-quinazoline;

2- 4-amino-phenyl) -4-phenyl-quinazoline;

2-phenyl-4- 4-di-methyl-amino-phenyl) -7 -methoxyquinazoline;

1,3-diphenyl-tetrahydr0imidazole;

1,3 -di- (4-chlorophenyl) -tetrahydroimidazole;

1,3-diphenyl-2,4'-dimethyl amino phenyl-tetrahydroimidazole;

1,3 ,-di- (p-tolyl) -2- [quinolyl- 2-) ]-tetrahydroimidazole;

3 (4-dimethylamino-phenyl) -5-4-methoxypheny1- 6-phenyl-1,2,4-triazine;

3-pyridil- (4) -5- 4"-dimethyl-amino-phenyl) -6- phenyl- 1 ,2,4-triazine;

3 (4'-amino-phenyl -5,6,-di-pheny1- l ,2,4-triazine;

2,5 -'bis [4-amino-phenyl-( 1') l ,3 ,4-triazole;

1,5 -diphenyl-3-methyl-pyrazoline;

1,3,4,Stetraphenyl-pyrazoline;

l-methyl-Z- (3 4-dihydroxy-methylene-phenyl) 'b enzimidazole;

2- 4-dimethylamino phenyl -benz0xazole;

2- (4-methoxyphenyl -benzthiazole;

2,5 -bisp-aminophenyl- 1 1 ,3,4-oxidiazole;

4, S-diphenyl-imidazolone;

3 ,-aminocarbazole;

copolymers and mixtures thereof. Any suitable Lewis acid (electron acceptor) may be employed under complexing conditions with many of the aforementioned more soluble organic materials and also with many of the more in soluble organics to impart very important increases in photosensitivity to those materials. Typical Lewis acids are:

2,4,7-trinitro-9-fluorenone; 2,4,5 ,7-tetranitro-9-fiuorenone; picric acid; 1,3,5-trinitrobenzene chloranil; benzo-quinone 2,5-dichlorobenzoquinone;

5 2-6-dichlorobenzo-quinone; chloranil; naphthoquinone- 1,4); 2,3-dichloronaphthoquinone-( 1,4); anthraquinone; Z-methyl-anthraquinone; l,4-dimethyl-anthra-quinone; l-chloroanthraquinone; anthraquinone-Z-carboxylic acid; l,5-dichloroanthraquinone, l-chlorO-4-nitroanthraquinone; phenanthrene-quinone; acenaphthenequinone; pyrantherenequinone; chrysene-quinone; thio-naphthenequinone; anthraquinone-1,8-disulfonic acid and anthraquinone- Z-aldehyde; triphthaloyl-benzene-aldehydes such as bromal, 4-nitrobenzaldehyde; 2,6-di-chlorobenzaldehyde-Z, ethoXy-l-naphthaldehyde; anthracene-9-aldehyde; pyrene-3-aldehyde; oxindole-3-aldehyde; pyridine-2,6-dialdehyde, biphenyl-4-aldehyde;

organic phosphonic acids such as 4-chloro-3-nitr0-benzene-phosphonic acid; nitrophenols; such as 4-nitrophenol and picric acid; acid anhydrides; for example, aceticanydride, succinic anhydride, maleic anhydride; phthalic anydride, tetrachlorophthalic anhydride; perylene 3,4,9, 10-tetracarboxylic acid and chrysens-2,3,8,9-tetracarboxylic anhydride; di-bromo maleic acid anhydride; metal-halides of the metals and metalloids of the groups I-B, II through to group VIII of the periodical system, for example: aluminum chloride, zinc chloride, ferric chloride tin tetrachloride, (stannic chloride); arsenic trichloride; stannous chloride; antimony pentachloride, magnesium chloride, magnesium bromide, calcium bromide, calcium iodide, strontium bromide, chromic bromide, manganous chloride, cobaltous chloride, cobaltic chloride, cupric bromide, ceric chloride, thorium chloride; arsenic tri-iodide; boron halide compounds, for example: boron trifluoride and boron trichloride; and ketones, such as acetophenone benxophenone; Z-acetyl-naphthalene; benzil; benzoin; S-benzoyl acenaphthene, biacene-dione, 9- acetylanthracene, 9-benzoyl anthracene; 4- (4-dimethylamino-cinnamoyl) 1 acetylbenzene; acetoacetic acid anilide; indandine-(l,3), (1,3 diketo hydrindene); acenaphthene quinone-dichloride; anisil, 2,2-pyridil; furil; mineral acids such as the hydrogen halides, sulphuric acid and phosphoric acid; organic carboxylic acids; such as acetic acid and the substitution products thereof; monochloro-acetic acid; dichloro-acetic acid; trichloro-acetic acid; phenylacetic acid; and 6-methyl-coumarinylacetic acid (4); maleic acid, cinnamic acid; benzoic acid; l-(4- diethylamino-benzoyl) benzene 2 carboxylic acid; phthalic acid; and tetrachlorophthalic acid; alpha-beta-dibromo-beta-formyl-acrylic acid (mucobromic acid); dibromo-maleic acid; Z-bromo-benzoic acid; gallic acid;

3-nitro-2-hydroxyl-l-benzoic acid; 2-nitro phenoxy-acetic acid; 2-nitro-benzoic acid;

3-nitro benzoic acid; 4-nitro-benzoic acid; 3-nitro-4-ethoxy-benzoic acid; 2-chloro-4-nitro-l-benzoic acid; 3-nitro-4-methoxy-benzoic acid; 4-nitro-l-methyl-benzoic acid; 2-chloro-5-nitro-l-benzoic acid; 3-chloro-6-nitro-l-benzoic acid; 4-chloro-3-nitro-l-benzoic acid; 5-chloro-3-nitro-2-hydroxy-benzoic acid; 4-chloro-2-hydroxy-benzoic acid; 2,4-dinitro-l-benzoic acid;

2-bromo-5-nitro-benzoic acid; 4-chlorophenyl-acetic acid; 2-chloro-cinnamic acid; Z-cyano-cinnamic acid; 2,4-dichlorobenz0ic acid; 3,5-dinitro-benzoic acid;

3,5-dinitro-salicylic acid; malonic acid; mucic acid; acetosalicylic acid; benzilic acid; butane-tetra-carboxylic acid; citric acid; cyano-acetic acid; cyclo-hexane-dicarboxylic acid; cyclo-hexane-carboxylic acid; 9,10-dichlorostearic acid; fumaric acid; itaconic acid; levulinic acid; (levulic acid); malic acid; succinic acid; alpha-brorno-stearic acid; citraconic acid; dibromo-succinic acid; pyrene- 2,3,7,8-tetra-carboxylic acid; tartaric acid; organic sulphonic acid, such as 4-toluene sulphonic acid; and benzene sulphonic acid; 2,4-dinitro-l-methyl-benzene-6-sulphonic acid; 2,6 dinitro-l-hydroxy-benzene-4-sulphonic acid and mixtures thereof.

In addition, other photoconductors may be formed by complexing one or more suitable Lewis acids With polymers which are ordinarily not thought of as photoconductors. Typical polymers which may be complexed in this manner include the following illustrative materials: polyethylene terephthalate, polyamides, polyimides, polycarbonates, polyacrylates, polymethylmethacrylates, polyvinyl fluorides, polyvinyl chlorides, polyvinyl acetates, polystyrene, styrene-butadiene copolymers, polymethacrylates, silicone resins, chlorinated rubber, and mixtures and copolymers thereof where applicable; thermosetting resins such as epoxy resins, phenoxy resins, phenolics, epoxyphenolic copolymers, epoxy ureaformaldehyde copolymers, epoxy melamine-formaldehyde copolymers and mixtures thereof, Where applicable. Other typical resins are epoxy esters, vinyl epoxy resins, tall-oil modified epoxies, and mixtures thereof where applicable.

It is also to be understood in connection with the heterogeneous system, that the photoconductive particles themselves may consist of any suitable one or more of the aforementioned photoconductors, either organic or inorganic, dispersed in, in solid solution in, or copolymerized with, any suitable insulating resin whether or not the resin itself is photoconductive. This particular type of particle may be particularly desirable to facilitate dispersion of the particle, to prevent undesirable reactions between the binder 14 and the photoconductor or between the photoconductor and the activator and for similar purposes. Typical resins of this type include polyethylene, polypropylene, polyamides, polymethacrylates, polyacrylates, polyvinyl chlorides, polyvinyl acetates, polystyrene, polysiloxanes, chlorinated rubbers, polyacrylonitrile, epoxies, phenolics, hydrocarbon resins and other natural resins such as rosin derivatives as well as mixtures and copolymers thereof.

The ratio of photoconductor 13 to binder 14 by volume in the heterogeneous system may range from about 10 to 1 to about 1 to 10, but it has generally been found that proportions in the range of from about 1 to 2 to about 2 to 1 produce the best results and, accordingly, this constitutes a preferred range.

As stated above, imaging layer 12 has relatively low cohesive strength either in the as-coated condition or after it has been suitably activated. This, of course, is true for both the homogeneous system and the heterogeneous system. One technique for achieving low cohesive strength in layer 12 is to employ relatively weak, low molecular weight materials therein. Thus, for example, in a single component, homogeneous layer 12, a monomeric compound or a low molecular weight polymer complexed with a Lewis acid to impart a high level of photoresponse to the layer may be employed. Similarly, when a homogeneous layer utilizing two or more components in solid solution is selected to make up layer 12, either one or both of the components of the solid solution may be a low molecular weight materials so that the layer has the desired low level of cohesive strength. This approach may 7 also be taken in connection with the heterogeneous layer 12 illustrated in FIG. 1. Although the binder material 14 in the heterogeneous system may in itself be photoresponsive, it does not necessarily have this property so that materials such as microcrystalline wax, paraffin wax, low molecular weight polyethylene and other low molecular weight polymers may be selected for use as this binder material solely on the basis of physical properties and the fact that they are insulating materials without regard to their photoresponse. This is also true of the two-com ponent homogeneous system where non-photoresponsive materials with the desired physical properties can be used in solid solution with photoresponsive material. Any other technique for achieving low cohesive strength in imaging layer 12 may also be employed. For example, suitable blends of incompatible materials such as a blend of a polysiloxane resin with a polyacrylic ester resin may be used either as binder layer 14 in a heterogeneous system or in conjunction with a homogeneous system in which the photoresponsive material may be either one of the incompatible components (complexed with a Lewis acid) or a separate and additional component of the layer. The thickness of imaging layer 12 is not critical and layers from about 0.5 to about 10 microns have "been used.

Receiving sheet 16 having a uniform duplicating layer thereon is in contact with imaging layer 12. Although the entire manifold set may be supplied in a convenient four-layer sandwich as shown in FIG. 1, the receiver sheet having coating 15 thereon can be supplied as a separate member which does not initially adhere to layer 12. In the particular embodiment of the manifold set shown in FIG. 1, both the donor substrate 11 and the receiver sheet 16 are made up of an electrically conductive material, such as cellophane, with at least one of them being optically transparent to provide for the exposure of imaging layer 12.

Duplicating layer 15 includes a large proportion of a soluble copy-producing material dispersed throughout a suitable binder material. The term copy-producing material is intended to include any soluble dye material which, of itself, has a particular color, such as the dyes used in conventional spirit duplicating processes, as well as transferable materials of latent color potential which, when brought in contact with an appropriate reaction partner, produce an intensely colored substance. This intensely colored substance can then be transferred to a copy sheet or, if the reaction partner is coated on a copy sheet, the intensely colored substance will be formed directly thereon. Suitable spirit soluble materials are well known in the art and include, for example, crystal violet, methyl violet, malachite green, nigrosine, magenta, Victoria green, etc. Further suitable copy-producing materials include, for example, the color-forming reaction pairs disclosed in Gundlach et al. 3,170,395 and such disclosure is incorporated herein by reference. The binder for the duplicating layer may comprise any conventional wax or resin binders or mixtures thereof, such as paraffin wax, microcrystalline wax, petrolatum, beeswax, carnauba, ethyl cellulose, or the like. The duplicating layer may be made from a suitable combination of various waxes, resins, oils, and copy-producing materials. The duplicating layer may also contain photoresponsive materials, such as the ones used in layer 12, to cause it to respond in a similar manner when exposed to a pattern of light and shadow. The copy-producing material should be of such a nature that it is sufliciently soluble in a duplicating fluid, such as an alcohol mixture, that upon repeated moistening of the duplicating layer with the duplicating fluid, a portion of the copy-producing material will be repeatedly transferred to a plurality of copy sheets in a manner well known to those skilled in the art. Thus, when using a spirit soluble dye, such as crystal violet, a portion of the crystal violet will be transferred to each of the copy sheets until the soluble dye is depleted from the duplicating layer. When using the color reaction partners, a portion of one reaction partner will be transferred from the duplicating layer to the other reaction partner to form the intensely colored substance. Suitable solvents for transferring a portion of the copy-producing material include water, alcohol, benzene-acetone or the like. Further, upon activation of either the imaging material 12 or the duplicating layer 15 a strong bond should occur at the interface between these two materials when placed in face-toface contact. Because of this relatively strong bond being formed at the interface, subsequent fracturing of the imaging material and the duplicating layer during exposure will result in a portion of the imaging material being transferred from the donor substrate to the receiver sheet thereby covering such portions of the duplicating layer which are not simultaneously transferred to the donor substrate. The duplicating layer is stripped away from the receiver sheet and transferred, as an overcoating, to the non-transferred portions of the imaging material supported by the underlying donor substrate. The donor substrate with the overcoating of duplicating layer bonded to the imaging material is the duplicating master of the present invention. Whether the duplicating master is a positive or negative of the original will depend on the photosensitive materials employed in the imaging layer 12 as well as the polarity of the applied field, as will be discussed hereinafter.

There should be a fairly close balance between the adherence of imaging layer 12 to the donor substrate 11 and the duplicating layer 15 to receiver sheet 16 with, preferably, a slightly stronger adherence of the imaging layer to the donor substrate at the time of imaging. Ac-. cordingly, substrate 11 and sheet 16 should be selected with this in mind. One way to easily accomplish this balance is to use the same material for sheet 16 as is used for substrate 11. As previously noted, upon activation of either the imaging material or the duplicating layer a strong bond, either adhesive or cohesive, should occur at the interface between the two materials when they are placed in face-to-face contact. This is most easily achieved by utilizing the same binder for the duplicating layer as for the imaging material. Accordingly, suitable binders include paratfin wax and microcrystalline wax. Upon activation, these layers form a strong cohesive interfacial bond resulting in a distinct two-phase material which will easily fracture during the application of the electric field and the exposure to a pattern of light and shadow. At least one of the donor substrate and the receiver sheet is transparent and, in fact, both may be transparent so that exposure may be made from either side of the manifold set. The manifold set may include separate electrodes on opposite sides of the donor substrate and receiver sheet for the application of the field or they may be directly on the back surfaces of these members and integral therewith. In another field application technique, one or both of the donor substrate and receiver sheet may be made of a conductive material. At least one of these is transparent so as to permit exposure of the imaging layer through this electrode. The imaging layer serves the dual function of imparting light sensi tivity to the system while at the same time acting as the colorant for at least one of the final images produced, although other colorant such as dyes and pigments may be added to it so as to intensify or modify the color of the final images produced when image color is important.

Although the structure of FIG. 1 represents one of the simplest forms which the manifold set may take, another embodiment is illustrated in FIG. 2 where imaging layer 12 may take any one of the forms as described above in connection with FIG. 1. In the FIG. 2 embodiment imaging layer 12 is deposited on an insulating donor substrate 17 which is backed with a conductive electrode layer 18. The remaining portion of the manifold set consists of a duplicating layer 15 deposited on an insulating receiver sheet 19 backed with a conductive electrode layer 21. As shown, layer .15 and imaging material 12 are in face-to-face contact. Here again, either or both of the pairs of layers 17-18 and layers 19-21 may be transparent so as to permit exposure of imaging layer 12. Flexible, transparent conductive materials, such as cellophane, which can be used in the FIG. 1 embodiment of the invention, are for the most part relatively weak materials with the choice of these materials being quite limited. The FIG. 2 structure which uses an insulating donor substrate and insulating receiver sheet 17 and 19, respectively, allows for the use of high strength insulating polymers such as polyethylene, polypropylene, Mylar (polyethylene terephthalate), cellulose acetate, Saran (vinyl chloride-vinylidene chloride copolymer) and the like. Not only does the use of this type of high strength polymer provide a strong substrate for the images formed but, in addition, it provides electrical barriers between the electrodes and imaging layer 12 and duplicating layer which tend to inhibit electrical breakdown of the system. Combinations of the structure described in FIGS. 1 and 2 may also be used in carrying out the invention with a relatively conductive layer immediately in contact with one side of imaging layer 12 and a conductively backed insulating layer on the other side of the manifold set in contact with the duplicating layer 15.

An alternate embodiment of the manifold set of the present invention is where the duplicating layer of the receiver sheet is overcoated with a thin layer of binder material utilized in the preparation of imaging layer 12. After activation of either layer, the manifold set is processed as previously described with the result that a portion of the duplicating layer is transferred from the receiver sheet to the donor substrate. It is advantageous to use this embodiment when using a different binder material for duplicating layer 15 than that used for imaging material 12 and where the adhesive interfacial forces are not sufficient to bond the two layers together. Thus, by previously manufacturing the receiving sheet, as described above, a strong bond can be created between these two materials at the factory and then during imaging a relatively strong cohesive bond can be created between the overcoating and the imaging layer 12. Optionally, the thin layer of binder material can contain a quantity of photoresponsive pigments and thus be similar in composition to imaging layer 12. An additional advantage of this embodiment is that the thin coating on the receiver sheet protects the duplicating layer from leaching during the activation operation in the event that the activator is a solvent for the dye contained within the duplicating layer.

Referring now to the flow of diagram of FIG. 3, it is seen that the first step in the imaging process is the activation step. In this stage of the imaging process, the manifold set is opened and the activator is applied either to imaging layer 12 or to duplicating layer 15 following which these layers are closed back together again, as indicated in the second block of the process flow diagram of FIG. 3. Although the activator may be applied by any suitable technique, such as with a brush, with a smooth or rough surfaced roller, by flow coating, by vapor condensation or the like. FIG. 3a which diagrammatically illustrates the first two process steps shows the activator fluid 23 being sprayed on to imaging layer 12 of the manifold set from a container 24. Following the deposition of this activator fluid, the set is closed by a roller 26 which also serves to squeegee out any excess activator fluid which may have been deposited. The activator serves to create an interfacial bond between imaging layer 12 and duplicating layer 15 as well as to weaken the cohesive strength of the combined imaging layers 12 and duplicating layer 15 (hereinafter called the combined imaging layer). That is, an interfacial bond is formed which is parallel to the surfaces of the donor substrate 11 and the receiving sheet 16 while the cohesive strength along lines perpendicular to these surfaces is lowered. The activator should also have a high level of resistivity so that it will not provide any electrically conductive paths through the combined imaging layer and, in addition, so that the combined imaging layer will support the electrical field which is applied therethrough during exposure. Accordingly, it will generally be found to be desirable to purify commercial grades of activators so as to remove impurities which might impart a higher level of conductivity to the activating fluids. This may be accomplished by running the fluids through a clay column or by any other suitable purification technique. Generally speaking, the activator may consist of any suitable solvent having the aforementioned properties and which has the above-described effect on the combined imaging layer. For purposes of this specification and the appended claims, the term solvent shall be understood to include not only materials which are conventionally thought of as solvents but also those which are thought of as partial solvents, swelling agents or softening agents for imaging layers 12 and 15. It is generally preferable that the activator solvents have a relatively low boiling point so that fixing can be accomplished after image formation by solvent evaporation with mild heating at most. It is to be understood, however, that r the invention is not limited to the use of these relatively volatile activators. In fact, very high boiling point nonvolatile activators including silicone oils such as dimethylpolysiloxanes and very high boiling point long chain aliphatic hydrocarbon oils ordinarily used as transformer oils, such as Wemco-C transformer oil, available from Westinghouse Electric Co., have also been successfully utilized in the imaging process. Although these less volatile activators do not dry off by evaporation, image fixing can be accomplished by rolling off the final image produced on an absorbent sheet such as paper which soaks up the activator fluid. In short, any suitable volatile or non-volatile solvent activator may be employed. Typical solvents include Sohio ordorless solvent 3440, an aliphatic (kerosene) hydrocarbon fraction, available from Standard Oil Co. of Ohio, carbon tetrachloride, petroleum ether, Freon 214 (tetrafluorotetrachloropropane), other halogenated hydrocarbons such as chloroform, methylene chloride, trichlorethylene perchloroethylene, chlorobenzene, trichloromonofluoromethane, tetrachlorodifluoroethane, trichlorotrifluoroethane, amides such as formamide, dimethyl formamide, esters such as ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, cyclohexyl acetate, isobutyl propionate and butyl lactate, ethers such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran, ethyleneglycol monoethyl ether, aromatic and aliphatic hydrocarbons such as benzene, toluene, Xylene, hexane, cyclohexane, gasoline, mineral spirits and white mineral oil, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone and vegetable oils such as coconut oil, babussu oil, palm oil, olive oil, castor oil, peanut oil and neatsfoot oil and mixtures thereof.

In certain instances, the first two steps of the imaging p1 ocess as diagrammatically illustrated in FIG. 3a, may be omitted. Thus, for example, a manifold set which is preactivated at the factory may be supplied. It is generally preferable, however, to include an activation step in the imaging process because, if this step is included, stronger and more permanent imaging layers 12 and 15 will be provided which can withstand storage and transportation prior to imaging and which will provide more permanent final images after imaging.

Once the proper physical properties have been imparted to imaging layers 12 and 15, an electrical field is applied across the manifold set and it is exposed to the image to be reproduced. Upon separation of substrate 11 and receiving sheet 16, the combined imaging layer fractures along the edges of exposed areas and at the surface where it is adhered to either substrate 11 or receiving sheet 16. Accordingly, once separation is complete portions of imaging layer 12 having an overcoating of duplicating layer 15 are retained on substrate 11 while the remaining portions adhere to sheet 16, through layer 15, resulting in the simultaneous formation of a high gamma positive image on one of the supporting members and a high gamma negative on the other. The supporting member having the duplicating layer overcoating will be the duplicating master of the present invention. Whether exposed portions are retained on donor substrate 11 or receiver sheet 16 will depend on the particular photoresponsive material employed in the imaging layer 12 as well as the polarity of the applied field. By making the initial degree of adherence of combined im aging layers 12 and 15 only slightly higher for substrate 11 than for sheet 16, the combined imaging layer is final- 1y retained on substrate 11 unless the combined effect of exposure and applied field is added to the bond strength of sheet 16 and the combined imaging layer, thereby exceeding the strength of the bond between the combined imaging layer and substrate 11. In this way, an amplification effect is achieved and transfer may be caused With relatively low levels of light exposure. The application of the required electrical field is relatively straightforward; however, with some materials, there is a preferred polarity orientation. Thus, for example, with an imaging layer 12 made up of finely divided metal-free phthalocyanine particles dispersed in a microcrystalline wax, the best images are formed when the donor is positioned at the illuminated electrode which is made negative and the non-illuminated electrode is positive. Accordingly, potential source 28, shown in FIG. 3b, is indicated as having its negative side connected to substrate 18 through which exposure is made by light rays 29. Field strengths in the range of about 500 to 4,000 volts per mil of thickness across the manifold set have been used to produce good images; however, the preferred field strength is on the order of LOGO-2,000 volts per mil. Knowing the thickness of the manifold set, the voltage to be applied to achieve imaging can easily be calculated.

In general, the receiver sheet 16 having duplicating layer 15 is rolled down onto the activated imaging layer 12 with the power on. However, to prevent air gap breakdown at the nip which will result in the production of Lichtenberg patterns, a fairly large resistance is preferably inserted in series with the power supply to limit the flow of current and the rate of charging of the capacitor which the manifold set forms. A fairly large resistor on the order of from about at least 5,000 to 20,000 megohms satisfactorily performs this function although the largest value resistors increase the gamma somewhat. This resistance may be omitted if sheet closure occurs before the field is applied. However, even then the resistor is preferably retained in the circuit to provide protection for the operator and limit the energy in a spark when occasional "breakdown occurs in flaws or pinholes in the Mylar. Another important function of this resistor, which is shown as resistor 30 in FIG. 3B, is that it provides a path for discharging the capacitor at an adequate rate to prevent sparking during separation of the donor substrate and the receiver sheet.

A visible light source, an ultraviolet light source or any other suitable source of actinic electromagnetic radiation may be used to expose the manifold set of this invention. Better quality images are produced by exposing from the donor side of the imaging layer and, accordingly, the receiver sheet 16 is usually separated from the other layers of the manifold set just after image exposure and generally with the power on both electrodes. This operation involves a current flow because as the layers are separated the capacitance of the manifold set is reduced and charge stored in this capacitor is caused to flow back through the resistor in the circuit which dissipates this current as an 1 R heat loss. Short delays in separation after the exposure step seem to have no deleterious ef fects on the images produced, Essentially, the same result 12 is produced if separation occurs after the power is turned off because the charge stored in the capacitor which is formed by the manifold set still applied a field across the combined imaging layer but generally poorer images result. It is to be noted that even when the power supply is turned off, it still acts as part of a closed circuit connecting the resistor to the two electrodes of the manifold set because of the LC filter network in the output of this type power supply. It is believed that a charge differential is built up between exposed and unexposed areas of layer 12 during the process so that when substrate 11 and sheet 16 are separated, the applied field causes imagewise portions of layer 12 to go with receiver sheet 16 while the complimentary or background areas are retained on substrate 11 to which layer 12 adheres more strongly. Because of the interfacial bond formed between layer 12 and layer 15, the materials are transferred from one support mmeber to the other in accordance with the stronger adherence of the underlying material for its substrate.

If a relatively volatile activator is employed, such as petroleum ether or carbon tetrachloride, fixing of the image on the receiver sheet occurs almost instantaneously after separation of the layer because the relatively small quantity of activator in the thin imaging layer flashes off rapidly. With somewhat less volatile activators, such as the Sohio odorless solvent 3440 or Freon 214, described above, fixing may be accelerated by blowing air over the images or warming them to about F., whereas With the even less volatile activators, such as transformer oil, fixing is accomplished by absorption of the activator into another layer such as a paper substrate to which the image is transferred. Many other fixing techniques and methods for protecting the images such as overcoating, laminating with a transparent thermoplastic sheet and the like will occur to those skilled in the art. Increased image durability and hardness may also be achieved by treatment with an image material hardening agent or with a hard polymer solution which will wet the image material but not the donor substrate.

In general, the apparatus for carrying out the imaging procedure described above will employ the elements illustrated in FIGS. 3a and 3b including means to apply the activator fluid, a squeegee roller to remove excess activator fluid, means to apply an electric field across the manifold set, means to expose the manifold set to a pattern to be reproduced, and means to separate the donor substrate and receiver sheet after imaging. Opening the manifold set for activation, closing the set for exposure and opening again for separation nad image formation may be accomplished by any one of a number of techniques which will be obvious to those skilled in the art. However, one straight-forward way to accomplish this result is to supply the imaging materials in the form of long webs which can be entrained over rollers so as to provide opening and closing of the set during the imaging process.

The spirit duplicating master of the present invention will be used in a manner well known to those skilled in the art. In general, the master is repeatedly brought into surface contact with copy sheets which have been moistened with a solvent for the dye material. A portion of the dye within the spirit duplicating layer will be dissolved in the solvent, leached from that layer and transferred from the master to the copy sheet to form the copy. As is known, a substantial number of copies can be made from the master before the dye is totally consumed. Under normal spirit duplicating applications, the master is then discarded as it is no longer capable of being utilized to produce additional copies. An additional advantage of the present invention is that the master, after the spirit duplicating copies have been run therefrom, is still opaque in image areas and can be used as a projection transparency. Whether this transparency will either be a positive or negative will depend upon the manner in which the master was produced.

The color reaction-pair duplicating master of the present invention will be used in a manner similar to that described above with respect to a spirit duplicating master. That is, in general, the master is repeatedly brought into surface contact with a plurality of copy sheets which have been moistened with a solvent for the reaction partner held on the surface of the master. A portion of the reaction partner within the duplicating layer will be dissolved in the solvent, leached from that layer and transferred from the master to the copy sheet to form the intensely colored substance in imagewise configuration. As with the spirit duplicating master, once the master is no longer capable of producing additional copies of high quality, the master can be used as a projection transparency.

The following examples are given to enable those skilled in the art to more clearly understand and practice the invention. They should not be considered as a limitation upon the scope of the invention but merely as being illustrative thereof.

EXAMPLE I A 2 mil thick Mylar receiving sheet is coated with a uniform spirit duplicating layer of crystal violet dispersed throughout a microcrystalline wax (Sunoco 1290) having a melting point of 178 F. The coating is microns thick and contains approximately 25% crystal violet by weight. A 5 micron thick uniform coating of metal free phthalocyanine in a microcrystalline wax (also Sunoco 1290) is deposited in subdued light upon a 2 mil thick Mylar sheet. The ratio of phthalocyanine pigment to wax binder is approximately 1:1. The coating on the donor substrate is heated to about 140 F. in darkness in order to dry it. The coated donor substrate is placed on a tin oxide surface of a NESA glass plate with its'phthalocyanine coating facing away from the tin oxide. The crystal violet coated side of the receiver sheet is placed face down on the coated surface of the donor substrate. Then, a sheet of black, electrically conductive paper is placed over the receiver sheet to form the complete manifold set. The receiver sheet is lifted up and the phthalocyanine-wax imaging layer is activated with one quick brush stroke of a wide camels hair brush saturated with petroleum ether. The receiver sheet is lowered back down and a roller is slowly rolled once over the closed manifold set with light pressure to remove excess petroleum ether. As shown in FIG. 3b, the negative terminal of an 8,000 volt DC power supply is connected to the NESA coating in series with a 5,500 megohm resistor, and the positive terminal is connected to the black opaque electrically conductive backing paper over the receiver sheet and then grounded. With the voltage applied, a white incandescent light image of approximately ft.-candle upward through the NESA glass for about 5 seconds. After exposure, the receiver sheet is peeled from the set with the potential source still connected. This separation yields a reversal of the original on the receiver sheet, the reversal areas comprising crystal violet dispersed throughout the microcrystalline wax binder overcoated with a layer of phthalocyanine also dispersed in a microcrystalline wax binder. The small amount of petroleum ether present evaporates within a second or two after separation and fixes the reversal image to the underlying receiver sheet. A spirit duplicating master corresponding to a duplicate of the original is produced on the donor substrate. The master comprises a Mylar substrate having, in on-exposed areas, a microcrystalline wax binder with phthalocyanine dispersed therein overcoated with a spirit duplicating layer of crystal violet dispersed throughout a similar microcrystalline wax binder. A substantial number of excellent spirit duplicating copies are made from this master, in accordance with procedures well known in the art, before copy quality deteriorates. The master is then placed in a projector and utilized as a projection transparency, the opaque areas of the imaging layer obstructing passage of the projected light thus yielding a projected image which corresponds to a duplicate of the original.

EXAMPLES II AND III The procedure of Example I is followed except in Example II Algol yellow GC Color Index No. 67,300 is used as the pigment in the imaging layer and in Example III the pigment is zinc oxide. After separation, a reversal of the original is formed on the receiver sheet and a spirit duplicating master corresponding to a duplicate of the original is produced on the donor substrate. A substantial number of excellent spirit duplicating copies are made from this master.

The main characterizing property of the system is that it is essentially a go or no go system, so that (l) the imaging layer either stays on the donor substrate or transfers to the duplicating layer on the receiver sheet and (2) the duplicating layer either stays on the receiver sheet (and is coated by the imaging layer) or transfers to the donor substrate (and coats the remaining imaging layer). Accordingly, there is the simultaneous production of a duplicating master and a raised relief image which can be used, for example, as a projection transparency.

While the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in the form and details may be made without departing from the true spirit and scope of the invention. Further, provided the advantageous results of this invention are not adversely affected, additional operations may be formed to achieve the herein disclosed results, or in certain circumstances, certain operations may be deleted as will be apparent to those skilled in the art. Numerous modifications may be made to adapt a particular situation or material to the teachings of the herein disclosed invention. All such additions, deletions, modifications, etc. are considered to be within the scope of the present invention.

What is claimed is:

1. An imaging member comprising a donor substrate, a photoresponsive imaging layer overlying said donor substrate, a duplicating layer contiguous with said photoresponsive layer, said duplicating layer comprising a copyproducing material selected from the group consisting of soluble dyes and latent color forming reaction partners said material dispersed in a binder material and a receiver sheet overyling said duplicating layer, at least one of said donor substrate and said receiving sheet being transparent to electromagnetic radiation which is actinic to said imaging layer and said imaging layer and duplicating layer being structurally fracturable in response to the combined effect of an electric field and actinic electromagnetic radiation.

2. The imaging member of claim 1 wherein the duplicating layer comprises a spirit soluble dye dispersed throughout a binder material.

3. The imaging member of claim 2 wherein the spirit soluble dye is a water soluble dye.

4. The imaging member of claim 2 wherein the spirit soluble dye is an alcohol soluble dye.

5. The imaging member of claim 1 wherein the duplicating layer comprises a latent color forming reaction partner dispersed throughout a binder material, said latent color-producing material reacting with a reaction partner on a copy sheet to produce an intensely colored substance.

6. The imaging member of claim 1 wherein said imaging layer comprises a particulate photoresponsive material dispersed in an insulating binder.

7. The imaging member according to claim 6 wherein said photoresponsive material comprises metal-free phthalocyanine.

8. The imaging member of claim 6 wherein said insulating binder is a wax.

9. The imaging member of claim 6 wherein said insulating binder is a low molecular weight polymer.

10. The imaging member of claim 6 wherein the duplicating layer contains a particulate photoresponsive material.

11. An imaging member of claim 1 wherein at least one of said donor substrate and said receiver sheet is backed with a conductive electrode layer.

12. An imaging member comprising a donor substrate; a photoresponsive imaging layer coated onto said donor substrate and comprising a particulate photoresponsive material dispersed throughout an insulating binder; a receiving sheet; a duplicating layer coated onto said receiving sheet and comprising a latent color forming reac tion partner material dispersed through a binder material; said photoresponsive imaging layer and said duplicating layer being in face-to-face contact and being structurally fracturable in response to the combined effect of an electric field and actinic electromagnetic radiation; and at least one of said donor substrate and said receiving sheet being transparent to electromagnetic radiation which is actinic to said imaging layer.

13. The imaging member of claim 12 frurther including an overcoating for said duplicating layer, said overcoating comprising a thin layer of the binder material for said photoresponsive imaging layer.

14. The imaging member of claim 12 wherein at least one of said donor substrate and receiving sheet is backed with a conductive electrode layer.

1.5. An imaging member comprising a donor substrate; a photoresponsive imaging layer coated onto said donor substrate and comprising a particulate photoresponsive material dispersed throughout a insulating binder; a duplicating layer coated onto said receiving sheet and comprising a soluble dye dispersed throughout a binder material; said photoresponsive imaging layer and said duplicating layer being in face-to-face contact and being structurally fracturable in response to the combined effect of an electric field and actinic electromagnetic radiation; and at least one of said donor substrate and said receiver sheet being transparent to electromagnetic radiation which is actinic to said imaging layer.

16. The imaging member of claim 15 wherein at least one of said donor substrate and receiving sheet is backed with a conductive electrode layer.

17. A method of imaging comprising exposing the imaging member of claim 1 to an electromagnetic radiation pattern actinic to said photoresponsive layer while simultaneously applying an electric field across said sandwiched member; and separating said donor substrate from said receiver sheet while under said field.

18. A method of imaging comprising applying an activator to a photoresponsive imaging layer coated on a donor substrate thereby rendering said layer structurally fructurable in response to the combined efiect of an electric field and actinic electromagnetic radiation; said activator selected from the group consisting of solvents, partial solvents, swelling agents and softening agents for said imaging layer; placing the duplicating layer coated side of a receiver sheet in contact with said activated photoresponsive imaging layer whereby said duplicating layer is also rendered structurally fracturable upon the fracture of said imaging layer said duplicating layer being selected from the group consisting of soluble dyes and latent color forming reaction partners dispersed in a binder; exposing said sandwiched member to an electromagnetic radiation pattern actinic to said photoresponsive layer while simultaneously applying an electric field across said sandwiched member; and separating said donor substrate from said receiver sheet while under said field.

19. A method of imaging comprising providing an imaging member having a donor substrate, a receiver sheet, and a combined imaging layer said layer being structurally fracturable in response to the combined effect of an electric field and actinic electromagnetic radiation sandwiched between said donor substrate and said receiver sheet, said combined imaging layer having a first zone adjacent said donor substrate and comprising a dispersion of a particulate photoresponsive material throughout an insulating binder, said combined imaging layer having a second zone adjacent said receiver sheet and comprising a copy-producing material selected from the group consisting of soluble dyes and latent color forming reaction partners dispersed throughout an insulating binder and bonded to said first zone, exposing said combined imaging layer to electromagnetic radiation pattern actinic to said first zone while applying an electric field across said imaging member; and separating said receiver sheet from said donor substrate while under said field so that said combined imaging layer fractures in imagewise configuration whereby a portion of said imaging layer is retained on one of said donor substrate and said receiver sheet while the remaining portion is retained on the other.

20. A method of imaging comprising providing a donor substrate having an overcoating of a dispersion of a particulate photoresponsive material within an insulating binder; providing a receiver sheet having an overcoating of a soluble dye material dispersed throughout an insulating binder, applying an activator to said overcoating on said donor substrate to render said overcoating structurally fracturable in response to the combined effect of an electric field and actinic electromagnetic radiation said activator selected from the group consisting of solvents, partial solvents, swelling agents and softening agents for said overcoatings; placing said receiver sheet over said donor substrate with said overcoatings in contact with each other whereby said overcoating on said receiver sheet is rendered structurally fracturable in response to the fracture of said imaging layer, exposing said combined overcoatings to an electromagnetic radiation pattern actinic to said photoresponsive overcoating while applying an electric field across said sandwiched member; and separating said receiver sheet from said donor substrate while under said field so that said combined overcoatings fracture in imagewise configuration, said donor substrate corresponding to a duplicating master having image defining areas comprising a layer of photoresponsive material sandwiched between a soluble dye material layer and said donor substrate, said receiver sheet having a reversed image from the image on said donor substrate, said reversed image comprising a layer of soluble dye material sandwiched between a layer of photoresponsive material and said receiver sheet.

References Cited UNITED STATES PATENTS 2,940,847 6/1960 Kaprelian 96--1 3,268,331 8/1966 Harper 96-1 3,316,088 4/1967 Schaffert 961.5 3,384,566 5/1968 Clark 204181 3,43 8,772 4/1969 Gundlach 96-1 CHARLES E. VAN HORN, Primary Examiner J. C. COOPER III, JR., Assistant Examiner U.S. Cl. X.R.

96-l.3, 1.4, 1.5, 27; l0ll50; 204-18, 

